what kind of surgery? When I had my gallbladder removed I was also not allowed to eat after midnight (actually I think it was 9pm) and not allowed to drink anything, even water, in the morning. The reason is because your stomach has to be empty for the surgery. If you overate especially food you're not used to, your stomach may not be empty. You need to tell your doctor / anesthesiologist in case it is a problem and the surgery needs to be put off for another day. If you feel like you want to vomit it may be best to go ahead and vomit but it is a really bad idea to overeat before surgery. I am pretty sure that I ate a small portion of yogurt around 7pm the night before I had surgery and nothing else because I had been warned that they aren't kidding about the meal cut-off, there is a reason they tell you that! Good luck, I hope it works out. Be honest with the doc.